Passive Checks House Rules

Let’s continue our series on Ability Checks with practical examples of house rules using passive checks. As a reminder, the passive score of an ability check is simply the “take 10” of that ability: 10 + ability modifier + proficiency if any. Another thing to keep in mind is that advantage translate to a +5 and disadvantage to a -5.

Passive Initiative

Remember that Dexterity is a dexterity check and that rolling initiative is a Dexterity contest between multiple creatures. Passive score can thus be defined as normal. From a house rule used by Jeremy E. Crawford and a mechanic used in other systems:
Instead of rolling initiative for monsters, you just write their passive initiative on their stats block (10+Dexterity modifier+ possible proficiency).

  • PROS: saving time for the DM, while still keeping the gleeful moment where you exclaim “Roll initiative!”.
  • CONS: it increases the number of enemies that can go at the same initiative, putting the group in more danger, since they cannot act or heal themselves between enemies turn as often. It also might disrupt the dynamism of combat.

Passive Investigation

Perception is king in many games — this is exacerbated by too many DMs not knowing that dim light impose disadvantage on (sight) perception checks. With a high score, not only can a PC see enemies before they attack,  detect traps, they also find secrets and notice key details, a standard that is used in many published adventures, such as Curse of Strahd. However, going by the skill description, Investigation could be used in some of those cases. Hence, you could use passive Investigation to determine if characters notice clues when entering a new location.


When the party enters a clockwork emporium to buy some gears, any character with a passive investigation higher than 15 notices that the shopkeeper keep drumming the counter in a specific pattern. Three slow taps, three quick taps; a common code in flying ship’s communications , a desperate plea for help. You quickly put two and two together and realize a hostage situation is going on.

Passive Arcana

When an enemy cast a spell, it can be critical to know its identity, or at least its school and level. Xanathar‘s Guide to Everything has an interesting rule that allow you to identify a spell, but for reasons related to synergy with counterspell — one of the best spells in the game — you need to expend your reaction. Here is a simple house rule:

When a creature that you can see within 60 ft of you cast a spell, if your passive arcana is equal or superior to 10 + spell level, then you immediately identify the spell. You have advantage if the spell is on your spell list, and automatically succeed if you know the spell.

Generalizing the previous examples

A more general formulation of the three previous house rules is to use a passive score whenever you do not want waste time with rolling. but want to communicate some information to the party. I recommend you write fluff content that you communicate only to the character with the highest passive score.

Example: Passive Religion.

When the party visit the temple of Bastet, inform the party member with the highest passive religion that Bastet is a goddess of the arts and war, and that her symbol is an ankh.

The big pro of this method is that bad luck on rolls does not curtail information from the players anymore. A problem familiar to many: the party need some information, you ask them for a roll, and they fail a roll. Now what? Using passive scores instead of rolls is a way to bypass the problem. It makes perfect sense in certain circumstances, such as common knowledge like the example above. Of course, there are other solutions. On the other hand, the method involves less rolling, and players love to roll ; it makes them feel in charge, and the physical act itself is fun.

Another way is to decide how the world reacts and what the party perceive or triggers, according to their passive score.

Example: Passive Charisma

While hunting a powerful enchanter, the party investigates a glamorous den of hedonistic plane-touched creatures, and supposedly worshipers of Sune. The party must pass through two large golden doors, who are guarded as it so happens by one Aasimar and one Tiefling. If any party member has a passive charisma less than 12, the Tiefling stops them at the door and deny them entry, simply saying “Sorry, you just won’t do. You are not shining right”, while trying to intimidate the character with their glowing eyes. If the party does not force the issue and the singled character leaves, the Aasimar pursue them, apologize profusely for her colleague harsh words, and try to sell them a pink-colored philter that would make their aura shine.

What happens if they buy it and drink it, I am sure you can tell.

Game-design philosophies: Free-will or Fate

Let us take a step back and examine active checks and passive checks. Rolls are great because they enhance fun at the table, involve the players, and give shape to the game flow. Passive checks save time and prevent bad luck from ruining options and breaking the flow. They are logical numbers to use for low-key rolls. But what do those two checks mean from a philosophical point of view?

Active checks and rolls follow the old principle of Action-Reaction. The characters act on the world, and the world reacts, and vice-versa. People roll and the dice issue their edict. Actions have consequences, one of the core principles of good RPGs (and my mantra). A farmer lucky enough could wound a dragon, and a dragon that rolls a critical failure would miss the farmer. But rather than luck, I would use the world chance.

In our example, we have used passive checks score as a sort of IF THEN ELSE structure in our notes, to avoid bad rolls that break the game’s flow, save time and still delivering maximum flavor to your players. In a way, this a manner to model fate. Their current state (their passive score) determine the outcome, and there is no place for chance. This is why the Player’s Handbook mentions you can use passive checks in situation where a party member repeats an action over and over again. In terms of game flow, it is a way of saying that the repeated action itself is uninteresting to narrate, and that we should get on with the rest of the adventure.

All of that seem obvious, but it is important sometimes to remember that mechanics are not just mechanics. They are innately tied to the game’s philosophy and its flavor.

Prepping the session

Running multiple passive scores might prove to be too much. After all it is already hard to track the characters HP, AC, abilities score, proficiency skills, spell slots, passive perception and so on — not that you have to track any of those. To remedy that, during your prep simply write everyone’s relevant passive scores down.

Diceless Dungeons&Dragons

To end this article, I shall mention a very peculiar house rule that you might not believe. I know of a DM who runs his game with almost no rolls and use passive scores, a perspective that does not appeal to me whatsoever. But I can see how this can create interesting tactical situations, where the players must get advantage (+5 on active) or small bonuses, give their target disadvantage (-5 on passive) or small maluses, as that create a +10 spread right from the start between the rolls.


Next week, I shall discuss how to make the ability score Intelligence more appealing in the game, both by using rules as written and house rules. Follow me on Twitter for updates!

Invade the Material Plane

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